Chinese Hackers discovered second Android master key vulnerability
Jul 16, 2013
Android Security Squad, the China-based group that uncovered a second Android master key vulnerability that might be abused to modify smartphone apps without breaking their digital signatures. The whole point of digitally signing a document or file is to prove the file hasn't been modified. The process uses a form of public-key cryptography . In Chinese version of hacking attack, malicious code can be added into the file headers, but the method is limited because targeted files need to be smaller than 64K in size. APK files are packed using a version of the widespread ZIP archiving algorithm. Most ZIP implementations won't permit two same-named files in one archive, but the algorithm itself doesn't forbid that possibility. So basically, two versions of the classes.dex file are placed inside of the package, the original and a hacked alternative. When checking an app's digital signature, the Android OS looks at the first matching file, but when act...